Recovery Plan for the Northern Spotted Owl - DRAFT

ment of interest (e.g., the entire range). The model contains information aboutthe environment, including the initial location of owls, and a series of rulesgoverning births, deaths, and movements. These rules are used in a stochasticsimulation of births, deaths, and movements during a year. At the end of theyear, the locations of all owls are again recorded, and then they are used forthe second year of the simulation. This process is repeated for as long a periodas the user desires. The model permits up to six cell types, three age classes,and two sexes, with possibly different demographic rates. The rules for movementsby juveniles and adults are flexible and permit simulation of a widevariety of behaviors. Additional details are contained in McKelvey (1991).The Recovery Team convened an advisory committee of biologists to providerecommendations on the use of the landscape model. The committee compileddata of value in determining the parameters required by the model and maderecommendations about certain structural changes. The advisory committeehas not finalized recommendations, but intends to do so during the coming fewmonths. Preliminary recommendations have been developed for habitat-specificproductivity, juvenile survival rates, and adult survival rates for Washingtonand Oregon west of the Pacific crest and north of the Klamath provinces. Themodel appears powerful, flexible, and capable of realistic simulations. Considerablework is needed, however, to make the model operational. The followinginformation is of particular importance:1. Habitat specific productivity and survival.Preliminary estimates are available for portions of the range, but in otherportions we do not have definitions for cell types. The needed informationcould be collected using two general approaches. First, home ranges ofbirds being monitored for productivity and adult survival should be assignedto cell types so that a sample for each type could be obtained. Second,intensive studies of transmittered birds should be made to improve ourunderstanding of habitat types that are used and avoided. Study shouldalso be made of the particular values to owls provided by each stand type.Much work of this sort has been done in western Oregon and Washington,but similar studies are needed (and in some cases are in progress) in environmentseast of the Cascades crest, in California, and in the OregonKlamath province. Habitats of particular interest should be selected forthese studies.2. Effects of habitat on movements by dispersing juveniles.This topic has received little study but is critical for the evaluation of therecommended DCA network. Intensive monitoring of dispersing juveniles isneeded to reveal how their movements and survivorship are affected by theconfiguration of habitat in the landscape they pass through, how widely theysearch for territories during dispersal, whether they settle in the first availableplace, and how far they travel if vacancies are not available. Closemonitoring of a relatively small number of birds (rather than occasionallocation of a larger sample) is needed. Monitoring such a sample of dispersingbirds, and analysis of the habitats and resident owls in their path, wouldprovide a far better basis than we have at present for deciding on the valuesof the movement parameters in the landscape model. Such studies might becarried out in the density areas where the locations of other owls are alreadywell known.3. Behavior of nonterritorial adultsNonterritorial adults may buffer the population against loss of breedingadults if the floaters rapidly fill vacancies (Franklin In Press). At present,267